There are various defects that appear during the manufacturing of digital cameras. One serious defect (that can result in a camera specimen being rejected during manufacture testing) is dark signal non-uniformity (DSNU). This defect may be manifested as a blob that appears when a digital image of a test scene captured by a unit or device under test (DUT) is displayed. The blob may be of any shape and usually appears as a color drift. Image processing-based detection algorithms are available that can be used to screen out DUTs whose test images exhibit the symptoms of such defects. A goal of such algorithms is to flag only those units that have the defects; efforts are under way to improve the accuracy of such algorithms, so as to reduce the likelihood of false positives, and to yield faster manufacture testing algorithms.